a) Field of the Invention
The present invention relates to apparatus and method for determining a presence or absence of a foreign object or the like is caught in a power open-and-closure mechanism such as a power window installed on an automotive vehicle, a power sun roof installed on a ceiling of a passenger compartment of the automotive vehicle, a power door closure mechanism, or the like without using a special-purpose sensor such as a torque sensor.
b) Description of the Related Art
A Japanese Patent Application First Publication No. Heisei 6-253570 published on Sep. 9, 1994 exemplifies a previously proposed motor control apparatus for a power open-and-closure mechanism which can determine whether a foreign object or the like is caught in the power open-and-closure mechanism.
In the above-identified Japanese Patent Application First Publication, an external motor disturbance force imposed on a motor as a load and generated due to a foreign object such as a human body or the like being caught in the power open-and-closure mechanism (hereinafter, referred simply to as an external disturbance force) is calculated from a motor drive current and a motor terminal voltage in addition to a motor angular acceleration.
Then, on the basis of the calculated external disturbance force imposed on the motor, the current flowing through the motor is controlled by means of a chopper operation using PWM (Pulse Width Modulation) pulses through a, so-called, H bridge drive circuit constituted by four cross-coupled semiconductor switching devices in such a way that the external disturbance force is reduced when an application of the external disturbance force to the motor driving the power open-and-closure mechanism occurs. Consequently, the foreign object or the like can be prevented from being continued to be caught in the power open-and-closure mechanism at a low cost.